//
// $Id: CssBackgroundImageCSS2.java,v 1.4 2008/03/25 18:43:30 ylafon Exp $
// From Philippe Le Hegaret (Philippe.Le_Hegaret@sophia.inria.fr)
//
// (c) COPYRIGHT MIT and INRIA, 1997.
// Please first read the full copyright statement in file COPYRIGHT.html

package org.w3c.css.properties.css1;

import org.w3c.css.parser.CssStyle;
import org.w3c.css.util.ApplContext;
import org.w3c.css.util.InvalidParamException;
import org.w3c.css.values.CssExpression;
import org.w3c.css.values.CssIdent;
import org.w3c.css.values.CssTypes;
import org.w3c.css.values.CssURL;
import org.w3c.css.values.CssValue;

/**
 *   <H4>
 *     &nbsp;&nbsp; 'background-image'
 *   </H4>
 *   <P>
 *   <EM>Value:</EM> &lt;url&gt; | none<BR>
 *   <EM>Initial:</EM> none<BR>
 *   <EM>Applies to:</EM> all elements<BR>
 *   <EM>Inherited:</EM> no<BR>
 *   <EM>Percentage values:</EM> N/A<BR>
 *   <P> This property sets the background image of an element. When setting a
 *   background image, one should also set a background color that will be used
 *   when the image is unavailable. When the image is available, it is overlaid
 *   on top of the background color.
 *   <PRE>
 *   BODY { background-image: url(marble.gif) }
 *   P { background-image: none }
 *   </PRE>
 * @version $Revision: 1.4 $ */
public class CssBackgroundImageCSS2 extends CssProperty {

    CssValue url;

    public static CssIdent none;
    private static final String property_name = "background-image";

    static {
	none = new CssIdent("none");
    }

    static public boolean checkMatchingIdent(CssIdent idval) {
	return none.hashCode() == idval.hashCode();
    }

    /**
     * Create a new CssBackgroundImageCSS2
     */
    public CssBackgroundImageCSS2() {
	url = none;
    }

    /**
     * Creates a new CssBackgroundImageCSS2
     *
     * @param expression The expression for this property
     * @exception InvalidParamException Values are incorrect
     */
    public CssBackgroundImageCSS2(ApplContext ac, CssExpression expression,
	    boolean check) throws InvalidParamException {

	if(check && expression.getCount() > 1) {
	    throw new InvalidParamException("unrecognize", ac);
	}
	
	setByUser();
	
	CssValue val = expression.getValue();
	switch (val.getType()) {
	case CssTypes.CSS_URL:
	    url = val;
	    break;
	case CssTypes.CSS_IDENT:
	    if (inherit.equals(val)) {
		url = inherit;
		break;
	    }
	    if (none.equals(val)) {
		url = none;
		break;
	    }
	default:
	    throw new InvalidParamException("value", val,
					    getPropertyName(), ac);
	}
	expression.next();
    }
    
    public CssBackgroundImageCSS2(ApplContext ac, CssExpression expression)
	throws InvalidParamException {
	this(ac, expression, false);
    }

    /**
     * Returns the value of this property
     */
    public Object get() {
	return url;
    }

    /**
     * Returns true if this property is "softly" inherited
     * e.g. his value equals inherit
     */
    public boolean isSoftlyInherited() {
	if (url != null) {
	    return inherit.equals(url);
	}
	return false;
    }

    /**
     * Returns a string representation of the object.
     */
    public String toString() {
	if (url != null) {
	    return url.toString();
	}
	return "";
    }

    /**
     * Returns the name of this property
     */
    public String getPropertyName() {
	return property_name;
    }

    /**
     * Add this property to the CssStyle.
     *
     * @param style The CssStyle
     */
    public void addToStyle(ApplContext ac, CssStyle style) {
	CssBackgroundCSS2 cssBackground = ((Css1Style) style).cssBackgroundCSS2;
	if (cssBackground.image != null) {
	    style.addRedefinitionWarning(ac, this);
	}
	cssBackground.image = this;
    }

    /**
     * Get this property in the style.
     *
     * @param style The style where the property is
     * @param resolve if true, resolve the style to find this property
     */
    public CssProperty getPropertyInStyle(CssStyle style, boolean resolve) {
	if (resolve) {
	    return ((Css1Style) style).getBackgroundImageCSS2();
	} else {
	    return ((Css1Style) style).cssBackgroundCSS2.image;
	}
    }

    /**
     * Compares two properties for equality.
     *
     * @param value The other property.
     */
    public boolean equals(CssProperty property) {
	return ((property == null && url == null)
		|| (property instanceof CssBackgroundImageCSS2 &&
		url != null &&
		url.equals(((CssBackgroundImageCSS2) property).url)));
    }

    /**
     * Is the value of this property is a default value.
     * It is used by all macro for the function <code>print</code>
     */
    public boolean isDefault() {
	return url == none;
    }

}